EP1851995B1

EP1851995B1 - Camera vision fire detector and system

Info

Publication number: EP1851995B1
Application number: EP06719767.3A
Authority: EP
Inventors: Lee D. Tice; Dragan P. Petrovic
Original assignee: Honeywell International Inc
Current assignee: Honeywell International Inc
Priority date: 2005-02-18
Filing date: 2006-01-27
Publication date: 2013-07-03
Anticipated expiration: 2026-01-27
Also published as: WO2006091328A3; US7495573B2; EP1851995A2; US20060188113A1; CN101248465A; WO2006091328A2; EP1851995A4

Description

FIELD OF THE INVENTION

The invention pertains to fire detection systems based upon camera vision. More particularly, the invention pertains to such systems which incorporate a predetermined beam of radiant energy into a region to be monitored for purposes of accurately determining the presence of smoke.

BACKGROUND OF THE INVENTION

A variety of different fire detection systems are known which utilize camera vision for purposes of monitoring the region. Signals from the camera or cameras in known systems, can be processed to evaluate flames within the field of view of the cameras.
Many of the known systems have a significant problem detecting smoke at night. They require that the lights in the region being monitored remain ON or that accessory lighting be provided in the area so the camera can detect changes. The primary problem with this is that a fire detecting system must have an ability to operate normally in the absence of power in the building. Therefore, at least some of the lighting would need to have battery back-up. The high power lighting of an area being monitored can make the battery back-up expensive. These systems often do not work well at night for detecting smoke in the absence of supplemental illumination. Flames can be detected at any time of day/night. Smoldering fires, however, are not readily detected in the absence of supplemental lighting which requires battery backup. Hence, these systems may not pass agency approvals as smoke detection systems.
Alternately, projected beam of smoke detectors are known. In these detectors, a beam of light is projected through an area being monitored. Exit beam characteristics are evaluated for the presence of smoke. While projected beam smoke detectors are useful and effective for their intended purpose, they represent an expense which is directed to implementing a single purpose function, namely smoke detection.
JP 2003/099876 discloses a system that determines the presence of smoke from the ratio of luminance from a light emitting device. It also calculates smoke density based on an average luminance calculated in a non-light-emitting region.
WO 2004/102498 discloses a smoke detector that detects smoke particles by emitting a beam of radiation to monitor a region and detecting a variation in images of the region indicating the presence of particles.
There continues to be a need for systems that are able to provide a fire detection function in combination with cameras which can also be used for security monitoring of an area or region. Such multi-purpose systems should be more cost effective than two separate systems. Additionally, such integrated systems may provide opportunities to cost effectively detect smoke under decreased lighting conditions or in dark regions.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 illustrates a camera configuration which does not for a part of the invention;
Fig. 1A is a block diagram of a smoke/flame regional monitoring system;
Fig. 2 illustrates an alternate camera configuration in accordance with the invention;
Fig. 3 illustrates another alternate camera configuration which does not form a part of the invention; and
Fig. 4 illustrates a further camera configuration which does not form a part of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

While embodiments of this invention can take many different forms, a specific embodiment thereof is shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiment illustrated.
System which embody the invention incorporate a modulatable source of radiant energy, visible or infra-red light. The radiant energy can be detected by a camera(s) that can also provide a security function. Use of the modulatable source enables such systems to detect smoke day or night.
Low power modulated sources can be used as they do not provide an over-all illuminating function. Only a relatively small portion of a region being monitored needs to be illuminated. Camera(s) local to a beam or beams from the source sense(s) the beam(s). Outputs from the camera(s) can be monitored for changes over time which may be indicative of smoke.
The camera responds to a beam from the modulated light source. A control system can, for example, monitor camera outputs for changes over time that may be indicative of a smoke condition. For example in a dark region (at night) the beam(s) noted above can be used for detection of smoke. Should a flaming fire break out it will provide an alternate source of illumination in the region and in the field(s) of view of the camera(s) which can be analyzed for indicia of a fire.
The alarm system can also energize local lighting to provide illuminated field(s) of view. Camera signals cannot only be analyzed for the presence of smoke or flame indicia, but images of the illuminated regions can also be viewed by security personnel. Such images could also be transmitted to the local fire department.
In the preferred system, a spatially interrupted pattern of light and dark regions is emitted to provide contrast. This pattern can be as simple as a black center surrounded by a ring of light. Alternately, a more complex pattern can be presented to the camera.
The camera's output signals are processed to determine the presence of a smoke condition. The light only needs to be visible to the camera and therefore may be infrared if the camera is sensitive to infrared. The output signals could also be processed to detect the presence of a flaming fire
In a system according to the invention, a camera views illumination of a displaced surface that has a light image projected onto it. This light image can be just a spot or a pattern of light.
In the disclosed embodiment, the light source can be implemented as a laser that projects a beam onto a displaced surface. The resulting illumination of the surface is captured by the camera and processed to determine the existence of a smoke condition. An advantage of this type of system is that the laser can be directly mounted to the camera such that small changes in angle of the camera will be followed with the laser and the illuminated image will not change relative to the camera view.
In another disclosed system not part of the invention, a camera views a displaced surface with the light source also located near that surface. The light is not projected across the sensing region. Hence, it can be projected with more complex patterns.
Alternately, the light source can just illuminate a pattern already existing on the illuminated surface. Such a pattern can be a black center circle surrounded by a white ring. The white ring is illuminated and provides a contrast with the black center that is visible both day and night.
In the above described embodiment and systems, the camera sends the picture information to a processor. The process executes locally available software to evaluate the picture information for the presence of smoke.
The camera views a change in illumination which will appear as a line if the light source is a laser. If an infrared source is used, then tins beam of light will not be detectable to persons in the area.
The camera sends the picture information to a processor for evaluation: The processor software will determine changes in the picture frames received and determine if there is a smoke condition or not. This processing can include digital signal processing.
In the above described system, the processor is looking for a illuminated line to form in the picture frames. This illuminated line is modulated to identify it with a fire system. When the line appears, it indicates that there is smoke in the region that is scattering light from the light beam (laser beam) causing it to become visible to the camera.
The processor can further analyze characteristics of the illuminated beam in determining a smoke condition. These characteristics can include, variations in ensity, changes in line length, uneven light intensity along the line, frequency, and time.
In another aspect, a processor aligns a center of a picture to an illuminated target. Portions of the illuminated target may be black. A change in in blackness to gray or the illuminated color or illuminated intensity can be detected. Smoke in the region will cause diffusion of light from the illuminated target so that the camera will not see the picture as clearly nor will it appear as black as when there is no smoke present.
Black colors at the target can be important because they will appear black for both day and night conditions. The light to black contrast can also be an important monitoring portion of the smoke detector. In addition, if there is other ambient lighting present, the change in contrast becomes even more severe with smoke. The system can be equipped to make adjustments for ambient light levels in determining the source of an alarm condition.
Ambient light will diffuse in the smoke. Hence, a region in the target will change more with the level of smoke than if ambient light is not present. Compensation can be incorporated to maintain a similar smoke sensing level for both light and dark conditions in the region.
Fig. 1 illustrates an exemplary camera configuration 1O. A camera Ci is illustrated therein with a field of view Vi which extends across a portion of a region R being monitored. A modulated light source 12 is mounted within the view Vi of the camera Ci. Source 12 could be spatially, temporally or frequency modulated all without limitation. In a preferred system, the light source 12 emits a pattern having light and dark regions (light and blocked light) such that viewing the light source provides light contrast. This pattern can be as simple as a black center surrounded by a ring of light. Alternately, it can have a detailed pattern that is viewed by the camera. As discussed in more detail subsequently, the camera Ci transmits image information, via a wired or wireless medium to a smoke or flame detection system for analysis.
Fig. 1A is a block diagram of an analysis system20 . As illustrated in Fig. IA, a plurality of cameras C1, C2 ... Cn can be mounted within a region R being monitored. The cameras each have a respective field of view V1, V2 ... Vn in a region or regions R being monitored. It will be understood that the fields of view for the respective cameras can but need not overlap one another.
The cameras C1, C2 ... Cn, which could be implemented as video cameras of various technologies are coupled wirelessly or via cables to a smoke/flame regional monitoring system indicated generally at 24. The system 24 includes a camera interface 26.
The interface 26 can incorporate one or more wireless communication antennas 28 for the receipt of wireless signals from one or more of the cameras Ci. Additionally, the interface 26 can incorporate circuitry for receiving, for example, video signals via hardwired cables K2 ... Kn all without limitation.
The system 24 also incorporates one or more programmable processors 30a which operate under the control of smoke/flame analysis software 30b. As noted above, the video signals received from a camera such as Ci of Fig. 1, carry information pertaining to the modulated light source 12.
The images from the camera Ci can be analyzed by the analysis software 30b as would be understood by those of skill in the art to determine if the changes present in the light from the modulated source 12 are indicative of the presence of smoke. In such event, the software 30b can communicate alarm indicating indicia to a regional security system 34 which would be monitored by security personnel.
The cameras C1, C2 ... Cn as would be understood by those of skill in the art, are also coupled to the security system 34. Camera images can be presented to an operator via security display 36. Additionally, system 24 can forward alarm indicating indicia to an alarm system display 38. Finally, a processor 30a can be coupled to a regional illumination control system 40.
In response to a determination of the presence of smoke or flame, the system 24 can signal the illumination control system 40 to illuminate some or all of the region R such as with cameras C1, C2 ... Cn can present illuminated images to the security personnel via display 36. Additionally, software 30b can continue analyzing
Figs. 2-4 illustrate alternate camera/source configurations usable with the system 20.
Fig. 2 illustrates a configuration 10-1 where a camera Cj has a field of view Vj which includes a section S of a wall or other surface. A modulated light source 44 is coupled to a housing for the camera Cj.
The modulated source 44 projects a beam of visible or infrared light 46 onto a portion S1 of section S in the field of view Vj. The image on portion S1 could be part of the incident beam, or, it could be a light pattern. The camera Cj can in turn transmit images of the illuminated portion Sl wirelessly or via cable Kj to system 24. Variations in the illuminated images on S1 when analyzed by software 30b can provide indicia indicative of the presence of smoke in the field of view Vj.
The configuration 10-1 has the advantage that the source 44 is directly coupled to the camera Cj. Hence, possibilities of misalignments between the field of view Vj and the location of incidence S1 of the beam can be minimized.
Fig. 3 illustrates an alternate camera/source configuration 10-2 which is not part of the invention. In Fig. 3, camera C1 has a field of view Vl directed toward a portion S' of a wall or surface. A modulated light source 48 projects a beam 50 onto a location S2 within the field of view V1. The light source 48 can for example, illuminate a pattern already existing on the illuminated surface. Such a pattern could have a black center circle surrounded by a white ring. The white ring is illuminated and provides a contrast with the black center that is visible both day and night.
The camera C1 can in turn transmit images to system 24 of the characteristics of the illumination S2. Software 30b can in turn analyze one or more of such images to establish the presence of a predetermined degree of smoke in the field of view V1.
Fig. 4 illustrates another camera configuration 10-3 which is not a part of the invention. A camera Cm has a field of view Vm and is coupled to transmit images wirelessly or via a wired medium, such as Km to system 24. The field of view Vm is directed toward and intersects a portion S" of a wall or surface.
A light source 54 which is located within the field of view Vm projects a beam 56 generally towards the camera Cm through the field of view Vm. Images from the camera Cm of the beam 56 will vary in accordance with the presence of smoke in the respective field of view Vm.
One of the advantages of system 10-3 is that the camera can monitor the light source to be sure it is operational at all times. In addition, smoke in the region will cause the beam of light to illuminate. The camera Cm can detect this change in
One of the advantages of system 10-3 is that the camera can monitor the light source to be sure it is operational at all times. In addition, smoke in the region will cause the beam of light to illuminate. The camera Cm can detect this change in illumination which will appear as a line if the light source 54 is a laser. If an infrared source is used, the beam of light 56 will not be visible by persons in the area. Processing can be carried out via software 30b to determine the presence of smoke in the region Vm as a result of changes in visibility of light beam 56.
In summary, in Fig. 4, the processor 30a can detect an illuminated line that has appeared in the picture frames. This illuminated line is modulated to associate it with a fire system. When the line appears, it indicates that there is smoke in the region that is scattering light from the light beam (laser beam) causing it to become visible to the camera Cm.
The processor 30a can analyze characteristics of the illuminated beam in determining a smoke condition. These characteristics can include, variations in intensity, changes in line length, uneven light through the line, projection of intersection of the line with the coordinates of the light source, etc. These characteristics can further include intensity, frequency and time.
From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the scope of the invention as defined by the appended claims. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.

Claims

An apparatus comprising:
a spatially modulated source (44) for projecting a beam (46, 50, 56) of visible or infrared light beam onto a portion S1 of a section S of a displaced surface;

a camera (Cj) having a field of view (Vj) including said section S of said displaced surface for capturing images of the illuminated portion S1, wherein said source (44) is directly mounted to said camera (Cj); and

control circuitry (24) for receiving images captured by said camera (Cj), analysing the received images to determine if there is an indication of the presence of smoke and communicating an alarm indicating indicia of the presence of smoke.
An apparatus as in claim 1 where the image captured by said camera comprises a human viewable image.
A system comprising an apparatus according to any one of the preceding claims, wherein the system further comprises a monitor (36) for presentation of a visual representation of the image captured by said camera.
A system as in claim 4 where the monitor is coupled to the camera by a communications network.
A method of detecting the presence of smoke, the method comprising the steps of:
spatially modulating a source (12, 44, 48, 54) for projecting a beam (46, 50, 56) of visible or infrared light beam onto a portion S1 of a section S of a displaced surface;

capturing images of the illuminated portion S1 with a camera having a field of view including said section S of said displaced surface, wherein said source is directly mounted to said camera;

receiving images captured by said camera;

analysing the received images to determine if there is an indication of the presence of smoke; and

communicating an alarm indicating indicia of the presence of smoke.